title: Effect of acute and regular exercise on growth hormone secretagogue receptor-1a expression in human lymphocytes, T cell subpopulation and monocytes.
abstract: The orexigenic peptide hormone ghrelin exerts potent inhibitory effects on pro-inflammatory cytokine release via the growth hormone secretagogue receptor-1a (GHS-R1a) on T cells and monocytes. As such, ghrelin is a promising therapeutic agent for the treatment of inflammatory conditions, but these effects depend on the availability of GHS-R1a. The aim of this study was to determine the effect of acute exercise on GHS-R1a expression on circulating CD14+ monocytes, total lymphocytes and CD3+ T cells. Nine male club-standard cyclists cycled for 1h at 75% V̇O2peak (EX) or rested (REST) in a randomised cross-over design. Compared with the equivalent times in REST, the concentration of circulating GHS-R1a+ lymphocytes and monocytes was higher in EX at immediately and 1 and 2h post-exercise (all p<.05). The concentration of CD3+GHS-R1a+ cells was higher in EX than in REST immediately post-exercise only (258 (203)cellsμl(-1) vs. 62 (42)cellsμl(-1), p<.05). Density of GHS-R1a receptor expression was unaffected by trial or time. Comparison of active participants at rest with 7 age-, sex- and BMI-matched sedentary controls revealed a higher concentration of GHS-R1a+ lymphocytes in active males (p<.05). These findings suggest a preferential recruitment of specific cell subpopulations expressing GHS-R1a into the peripheral circulation with acute and regular exercise. Given that the anti-inflammatory effects of ghrelin depend on the availability of GHS-R1a, the preferential recruitment of subpopulations with high anti-inflammatory potential found here add a novel aspect to the potential mechanisms by which exercise acts to reduce pro-inflammatory cytokine levels.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK. Electronic address: n.c.bishop@lboro.ac.uk.
authors.forename: Nicolette C
authors.initials: NC
authors.lastname: Bishop
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: Harumi
authors.initials: H
authors.lastname: Hayashida
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: Megan
authors.initials: M
authors.lastname: Clark
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Coombs
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Miller
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Stensel
mesh_terms: D000328:Adult; D017252:CD3 Complex / Q000378:metabolism; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D054439:Ghrelin / Q000097:blood; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D009000:Monocytes / Q000378:metabolism*; D054440:Receptors, Ghrelin / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism; D055815:Young Adult
chemical_list: D017252:CD3 Complex; D054439:Ghrelin; D018950:Lipopolysaccharide Receptors; D054440:Receptors, Ghrelin
keywords: Ghrelin; Growth hormone secretagogue receptor; Inflammatory; Monocyte; T cell